On a warm summer's afternoon, Alice Dean's husband takes their dog for a walk in the woods adjacent to their home in the village of Netherwell. Several hours later her husband has still not returned and is not answering his mobile phone. When the dog arrives home alone, Alice begins to fear the worst. Meanwhile a rambler discovers a badly mauled corpse and Dave French, a paramedic, is called out to attend. While examining the body, his co-worker brutally assaults him in an unprovoked attack. Over the course of the next two days, the idyllic rural location of Netherwell descends into a spiral of escalating violence where Alice and Dave must battle to survive in a world in which every living creature is a potentially lethal foe.